A 3-mile-wide comet named Neowise is passing Earth on a journey that will not happen again for another 6,800 years. Experts say the best time to see it is about an hour after sunset, under the Big Dipper constellation. The closest the comet will be to Earth is on July 22. (Courtesy: Santiago Andrés Triana / Royal Observatory of Belgium, Firmin Boyon, Bryce Bird)
